The invention concerns an optic device comprising a plurality of resonant cavities of different lengths associated with different wavelengths.
Such a device is, for example, intended to build on a single optoelectronic chip, an array of multiple wavelength lasers of VCSEL (vertical cavity surface emitting laser) type.
In the prior art, the variation in length of the resonant cavities of VCSEL-type laser array has been obtained by various processes, notably by successive engraving processes of different heights (EP-A-949728), by micromechanic displacement of a membrane (U.S. Pat. No. 5771253) or by controlling the epitaxial growth thickness of each cavity (EP-A-1030420).
However, these techniques are complex, notably because they require a particular technological step for each cavity length.
The aim of the invention is a device that does not exhibit the shortcomings of the previous devices.
According to the invention, this purpose is met in that each resonant cavity comprises a convex cap of preset thickness, of transparent material for said wavelengths, intended to determine the length of the related resonant cavity.
According to a development of the invention, the caps can be obtained by remelting cakes on the material forming the cavities.
The cakes have, preferably, different surfaces, in relation to the preset thickness of the corresponding cap.